User Persp implementation
As far as I understand it, a virtual camera is implemented in Blender. Blender users a GL library which implements it in some other way underneath though.

Could you tell what you are trying to achieve with this?

Edit:

(This is what I have gleaned by reading some of the source. If someone more versed into it can correct me, he or she should feel free to.)

If you dig into blender/editors/space_view3d/, you can find the actual implementation. In summary RegionView3D objects hold the reference to the area's perspective (and by extension what you refer to as a virtual camera) in the persp member variable. The reference to the physical camera object is held by View3D objects. These may or may not be the same. (Or rather the persp derived from View3D.camera may or may not be the same as RegionView3D.persp.)

Here is the view3d_setobjectascamera_exec function's code. It manipulates both cameras. I am on a phone right now, and I can only post a screenshot. It is from the 2.6 branch found on launchpad.